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As I recall, integer coordinates will refer to positions between
pixels. If you add 0.5 to your coordinates then you will draw the
line at the center of the pixel and it will be possible to have a
single pixel width line.<br>
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<div class="moz-cite-prefix">On 12/29/2015 3:00 PM, Christos
Sotiriou wrote:<br>
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cite="mid:CANp+zOFtwpKs_d_BYoeE0vA4Q9jMBPkA1U8oCjd1AbmXSqxVPg@mail.gmail.com"
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<div class="gmail_default" style="color:rgb(7,55,99)">Hello,<br>
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<div class="gmail_default" style="color:rgb(7,55,99)">for an
application using GTK and Cairo for its back-end I am drawing
to <b>integer</b> <b>coordinates</b> (cairo scale is 1) for
efficiency using simple cairo function calls.<br>
<br>
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<div class="gmail_default" style="color:rgb(7,55,99)">I would
like to draw single pixel lines. In Cairo version
cairo-1.14.0-2.fc20.x86_64, using a line width of <b>1 (or
1.0)</b> works fine.<br>
<br>
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<div class="gmail_default" style="color:rgb(7,55,99)">In Cairo
version 1.8.8-2.1.48 (Suse) a line width of 1 does not draw
the line at all, or draws halfway.<br>
<br>
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<div class="gmail_default" style="color:rgb(7,55,99)">When I
change the line width to <b>2 (or 2.0)</b>, the line is
drawn. I know that in the FAQ a line width of 2.0 is
recommended : <a moz-do-not-send="true"
href="http://cairographics.org/FAQ/#sharp_lines">http://cairographics.org/FAQ/#sharp_lines</a>.<br>
<br>
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<div class="gmail_default" style="color:rgb(7,55,99)">Is this
the only solution, i.e. to change the line width to 2.0? When
I do that the lines appear slightly thicker that I would like!<br>
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<div class="gmail_default" style="color:rgb(7,55,99)"><br>
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<div class="gmail_default" style="color:rgb(7,55,99)">Thank you
for your help,<br>
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<div class="gmail_default" style="color:rgb(7,55,99)"><br>
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<div class="gmail_default" style="color:rgb(7,55,99)">Christos.<br
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-- <br>
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<div>--------------------------------------------------------------------------<br>
Christos P. Sotiriou<br>
email: <a moz-do-not-send="true"
href="mailto:csotiriou@gmail.com" target="_blank">csotiriou@gmail.com</a><br>
Cell (GR): +30 697 8984 222<br>
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<div>Cell (US): +1 858 247 9436<br>
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